StarMirror/CppCoreGuidelines
1
0
Fork 0
mirror of https://github.com/isocpp/CppCoreGuidelines.git synced 2024-03-22 13:30:58 +08:00
Code Issues Projects Releases Wiki Activity

Clarify that finally() is a last resort

Browse Source 
E.6 and E.19
This commit is contained in:
Bjarne Stroustrup 2017-04-15 21:32:57 -04:00
parent a8572ad328
commit 6bcfaa4fbe
1 changed files with 11 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
CppCoreGuidelines.md
View File

@ -13512,7 +13512,9 @@ Flag classes with `private` state without a constructor (public, protected, or p
##### Reason
Leaks are typically unacceptable. RAII ("Resource Acquisition Is Initialization") is the simplest, most systematic way of preventing leaks.
Leaks are typically unacceptable.
Manual resource release is error-prone.
RAII ("Resource Acquisition Is Initialization") is the simplest, most systematic way of preventing leaks.
##### Example
@ -13526,7 +13528,7 @@ Leaks are typically unacceptable. RAII ("Resource Acquisition Is Initialization"
We could carefully release the resource before the throw:
void f2(int i) // Clumsy: explicit release
void f2(int i) // Clumsy and error-prone: explicit release
{
int* p = new int[12];
// ...
@ -13539,7 +13541,7 @@ We could carefully release the resource before the throw:
This is verbose. In larger code with multiple possible `throw`s explicit releases become repetitive and error-prone.
void f3(int i) // OK: resource management done by a handle
void f3(int i) // OK: resource management done by a handle (but see below)
{
auto p = make_unique<int[]>(12);
// ...
@ -13549,7 +13551,7 @@ This is verbose. In larger code with multiple possible `throw`s explicit release
Note that this works even when the `throw` is implicit because it happened in a called function:
void f4(int i) // OK: resource management done by a handle
void f4(int i) // OK: resource management done by a handle (but see below)
{
auto p = make_unique<int[]>(12);
// ...
@ -13567,9 +13569,12 @@ Unless you really need pointer semantics, use a local resource object:
// ...
}
That's even simpler and safer, and often more efficient.
##### Note
If there is no obvious resource handle, cleanup actions can be represented by a [`final_action` object](#Re-finally)
If there is no obvious resource handle and for some reason defining a proper RAII objct/handle is infeasible,
as a last resort, cleanup actions can be represented by a [`final_action`](#Re-finally) object.
##### Note
@ -13934,6 +13939,7 @@ Better:
`finally` is not as messy as `try`/`catch`, but it is still ad-hoc.
Prefer [proper resource management objects](#Re-raii).
Consider `finally` a last resort.
##### Note